Grinding machine



FIG. 1 is a front perspective view of a grinding machine embodying may new design;

FIG. 2 is a side elevational view thereof illustrating the side opposite to that illustrated in FIG. 1;

FIG. 3 is a front elevational view thereof;

FIG. 4 is a top plan view thereof; and

FIG. 5 is a rear elevational view thereof. 

The ornamental design for a grinding machine, substantially as shown. 